Country: Washington, Oregon, Idaho, Montana, Wyoming, North & South Dakota
Distribution of Terrestrial Snakes in North America
Pit Vipers
| Crotalus concolor | S | South Western Wyoming only |
| Crotalus lutosus | X | Western Oregon, Central and Southern Idaho |
| Crotalus oreganus | X | |
| Crotalus viridis | E | Montana, Western Idaho, Wyoming, Nortzh and South Dakota |